KR20230140500A - Copper-ceramic joint, brazing material, and method for manufacturing copper-ceramic joint - Google Patents

Abstract

Provided is a copper-ceramic joint having high bonding strength. The copper-ceramic joint comprises: a copper material which is made of Cu or a Cu alloy; a ceramic material which is bonded to the copper material, and is made of nitride of Si or Al; and a bonding layer which is formed on the bonding surface of the copper material and the ceramic material, includes Cu and Mg, and further includes at least one active metal element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ca, Y, Ce, La, Sm, Yb, Nd, Gd, and Er. The shear strength of the bonding layer is 10 MPa or more.

Description

Copper ceramic joint, brazing material and copper ceramic joint manufacturing method {COPPER-CERAMIC JOINT, BRAZING MATERIAL, AND METHOD FOR MANUFACTURING COPPER-CERAMIC JOINT}

The present disclosure relates to a copper ceramic bonded body, a brazing material, and a method of manufacturing a copper ceramic bonded body.

As a constituent material of a power control device mounted on an electric vehicle or a hybrid vehicle, a bonded body formed by bonding a copper material and a ceramic material (hereinafter also referred to as a copper-ceramic bonded body) is sometimes used. For joining copper materials and ceramic materials, the technology of using an active metal brazing material containing silver (Ag) is known, but in recent years, in order to solve problems such as Ag migration and high cost, the use of an active metal brazing material that does not contain Ag has been used. A joining technology has been proposed (for example, see Patent Document 1).

Japanese Patent Publication No. 2018-140929

The purpose of the present disclosure is to increase the bonding strength in a copper ceramic bonded body.

According to one aspect of the present disclosure,

A copper material made of Cu or Cu alloy,

A ceramic material bonded to the copper material and made of Si or Al nitride,

It is formed on the joint surface of the copper material and the ceramic material, and includes Cu and Mg, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ca, Y, Ce, La, Sm, Yb, It has a bonding layer further containing at least one active metal element selected from the group consisting of Nd, Gd, and Er,

The shear strength of the bonding layer is 10 MPa or more.

A copper ceramic joint is provided.

According to another aspect of the present disclosure,

It is used for joining a copper material made of Cu or Cu alloy and a ceramic material made of nitride of Si or Al,

Cu at 65 to 95 at%, Mg at 4.5 to 33 at%, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ca, Y, Ce, La, Sm, Yb, Nd, Gd, Er. Containing at least one active metal element selected from the group consisting of a total ratio of 0.1 to 7 at%

Lead material is provided.

According to another aspect of the present disclosure,

A process of arranging a copper material made of Cu or a Cu alloy and a ceramic material made of a nitride of Si or Al to be laminated with a brazing material interposed therebetween;

A step of heating and holding the laminate of the copper material and the ceramic material while pressing in the stacking direction,

As the brazing material, 65 to 95 at% Cu, 4.5 to 33 at% Mg, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ca, Y, Ce, La, Sm, Yb, Nd, Using a material containing at least one active metal element selected from the group consisting of Gd and Er in a total ratio of 0.1 to 7 at%

A method for manufacturing a copper ceramic joint is provided.

According to the present disclosure, it becomes possible to increase the bonding strength in a copper ceramic bonded body.

1 is an enlarged partial cross-sectional view of a copper ceramic bonded body 100 according to one aspect of the present disclosure.
FIG. 2 (a) is an enlarged partial cross-sectional photograph of the main part A of FIG. 1, and (b) is an enlarged partial cross-sectional photograph of the main part B of FIG. 1.
Figure 3 is an enlarged partial cross-sectional photograph of main part C of Figure 1.
FIG. 4 (a) is a diagram schematically showing the shear stress applied to the bonding layer 30, and (b) is a diagram schematically showing the tensile stress applied to the bonding layer 30.
Figure 5 (a) shows the copper material 10 and the ceramic material 20 arranged through the brazing material 50, and (b) shows the laminate of the copper material 10 and the ceramic material 20 being pressed. (c) is a diagram showing the manufactured copper ceramic bonded body 100 while heating.
Figure 6 is a diagram schematically showing how a shear strength test is performed.
Figure 7 is an enlarged photograph of a partial cross-section of the bonding layer in which a large void 33L has occurred.

<One aspect of the present disclosure>

Hereinafter, one aspect of the present disclosure will be described with reference to the above-described group of drawings. In addition, all drawings used in the following description are schematic. The dimensions or proportions of each element shown in the drawing do not necessarily match reality. Additionally, even between drawings, the dimensions and ratios of each element do not necessarily match.

(1) Composition of copper ceramic bonded body

As shown in FIG. 1, the copper ceramic joined body 100 includes a copper material 10 and a ceramic material 20 joined to the copper material 10.

The copper material 10 is made of pure copper (hereinafter also referred to as Cu) or copper alloy (hereinafter also referred to as Cu alloy). As pure copper, oxygen-free copper, tough pitch copper, and phosphorus deoxidized copper can be used, for example. Copper alloys include copper (Cu) as the main element, and include, for example, zinc (Zn), tin (Sn), phosphorus (P), aluminum (Al), beryllium (Be), cobalt (Co), and nickel (Ni). ), iron (Fe), and manganese (Mn). An alloy to which at least one element selected from the group is added can be used. There is no particular limitation on the shape or size of the copper material 10, but when the copper ceramic bonded body 100 is used as a constituent material of an insulating circuit board, the thickness is within the range of 0.1 mm to 4.0 mm, for example. You can do it with the reputation you have.

The ceramic material 20 is made of a sintered body made of nitride of silicon (Si) or aluminum (Al), that is, silicon nitride represented by the composition formula Si ₃ N ₄ or aluminum nitride represented by the composition formula AlN. There is no particular limitation on the shape or size of the ceramic material 20, but when the copper ceramic bonded body 100 is used as a constituent material of an insulating circuit board, the thickness is within the range of 0.2 mm to 4.0 mm, for example. You can do it with the reputation you have. Hereinafter, as an example, a case where the ceramic material 20 is made of silicon nitride will be described.

Between the copper material 10 and the ceramic material 20, a bonding layer 30 is formed along these bonding surfaces 10s and 20s. The bonding layer 30 contains copper (Cu), magnesium (Mg), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), and tantalum (Ta). , chromium (Cr), molybdenum (Mo), tungsten (W), calcium (Ca), yttrium (Y), cerium (Ce), lanthanum (La), samarium (Sm), ytterbium (Yb), neodymium (Nd). , gadolinium (Gd), erbium (Er), and the like. Hereinafter, as an example, a case where the active metal element is Ti will be described.

In addition, as will be described later, the bonding layer 30 includes a brazing material 50 (see FIG. 5) each containing Cu, Mg, and the above-mentioned active metal elements in a predetermined ratio, and the copper material 10 and the ceramic material. It is formed by reacting with each of (20). The brazing material 50 used in this embodiment does not contain Ag, and not only contains Mg and the above-mentioned active metal elements, but also contains Cu in a ratio described later. Also preferably, the brazing material 50 used in this embodiment contains Mg in the form of an intermetallic compound with Cu. By performing bonding using such brazing material 50, various characteristics shown below appear in the bonding layer 30 in this embodiment.

Hereinafter, various characteristics of the bonding layer 30 will be described.

(Feature 1)

As shown in FIG. 1, the bonding layer 30 is composed of the first layer 31 constituting the interface with the copper material 10 and the second layer 32 constituting the interface with the ceramic material 20. It has a layered structure. The thickness of the first layer 31 is 1 to 2000 μm, and the thickness of the second layer 32 is 1 to 2000 nm.

FIG. 2(a) and FIG. 2(b) respectively illustrate enlarged cross-sectional photographs of the first layer 31. These photos were taken of the first layer 31 and its surroundings from different observation positions. As shown in these photographs, the first layer 31 has a solid solution phase 31A and a compound phase 31B. The solid solution phase (31A) and the compound phase (31B) are phase-separated in a sea-island pattern. For example, the compound phase 31B is dispersed in the form of islands in the solid solution phase 31A of the sea phase, which is a continuous layer.

The solid solution phase 31A mainly contains a solid solution in which Mg is dissolved in Cu crystals. In the solid solution phase 31A, active metal elements such as Ti contained in the brazing material 50 or Si or Al contained in the ceramic material 20 may be dissolved in solid solution.

The compound phase 31B has as its main component an intermetallic compound of Cu and Mg, that is, a compound represented by the composition formula MgCu ₂ (hereinafter also referred to as Cu-Mg alloy). In the compound phase 31B, an intermetallic compound containing the above-mentioned active metal element may also precipitate. When Ti is selected as the active metal element, the intermetallic compound containing the active metal element has the composition formula Cu ₄ Ti, Cu ₃ Ti ₂ , Cu ₂ Ti, Cu ₄ Ti ₃ , CuTi, CuTi ₂ , Ti ₅ Si ₃ , At least one compound selected from the group of compounds represented by Ti ₃ Si, CuTiSi, etc. can be mentioned.

The compound phase 31B, which has an intermetallic compound as its main component, has a brittle characteristic compared to the solid solution phase 31A, which has a solid solution as its main component, and depending on the mode of appearance in the first layer 31, copper This may be a factor that significantly reduces the bonding strength between the material 10 and the ceramic material 20. This is because, in the case of using a brazing material containing Mg and the above-mentioned active metal elements alone and not Cu, for joining the copper material 10 and the ceramic material 20, the intermetallic compound is formed in the first layer. (31), it appears concentrated in the region D near the interface adjacent to the second layer (32). When the intermetallic compound appears concentrated in the area D near the interface, a weak layer structure is formed along the joint surface in the first layer 31, thereby reducing the joint strength between the copper material 10 and the ceramic material 20. is significantly reduced. Also, in this case, the joining of the copper material 10 and the ceramic material 20 may become impossible.

In response to this problem, in this embodiment, when joining the copper material 10 and the ceramic material 20, a brazing material 50 that not only contains Mg and an active metal element but also contains Cu in a ratio described later is used. By using it, local appearance of the compound phase (31B) in the first layer 31, for example, local appearance of the compound phase (31B) in the area D near the interface with the second layer 32 , succeeded in suppressing it.

Specifically, in this embodiment, when the first layer 31 is observed in a cross section perpendicular to the joint surfaces 10s and 20s of the copper material 10 and the ceramic material 20, the second layer 32 The interface vicinity area D adjacent to the interface, that is, a predetermined area within a thickness range of, for example, 10 μm, from the interface with the second layer 32 of the first layer 31 toward the copper material 10 side. In this case, the total cross-sectional area SA of the solid solution phase (31A) and the total cross-sectional area SB of the compound phase (31B) satisfy the relational formula of SA/(SA+SB)>0.6, preferably >0.7, more preferably >0.8. I'm doing it.

In addition, as shown in Figure 2 (a) and Figure 2 (b), the compound phase 31B in this embodiment is approximately the entire thickness direction and approximately the width direction of the first layer 31. Throughout the entire region, they are not concentrated locally, but are distributed with a roughly uniform frequency of appearance. Therefore, in this embodiment, not only the area near the interface D, but also any area in the first layer 31 excluding the area near the interface D (for example, any area on the side closer to the copper material 10 than the area near the interface D). In any of the regions, SA and SB satisfy the above-mentioned relationship. In other words, in this embodiment, when the first layer 31 is observed in a cross section perpendicular to the joint surfaces 10s and 20s of the copper material 10 and the ceramic material 20, the average value over the entire thickness direction is SA/(SA+SB) >0.6, preferably >0.7, more preferably >0.8, and any thickness within the first layer 31, for example, 10 μm. In any of the local regions, it can be said that SA/(SA+SB)>0.6, preferably >0.7, and more preferably >0.8 are satisfied.

Since the total cross-sectional areas SA and SB satisfy the above-mentioned relational expression, as shown in Fig. 2(a) and Fig. 2(b), respectively, in the first layer 31 of this embodiment, the compound phase 31B is localized. The weak layer structure that is formed as a result of adversarial activity does not appear. And, in the first layer 31, a path consisting of the solid solution phase 31A connecting the second layer 32 and the copper material 10 is secured. Since this pass contains a solid solution as the main component, it is excellent in ductility and malleability, and furthermore, the second layer 32 and the copper material 10 are continuously formed without being broken along the way by the brittle compound phase 31B. Connecting. This path constitutes a strong connection structure connecting the copper material 10 and the ceramic material 20.

(Feature 2)

When joining the copper material 10 and the ceramic material 20 using a brazing material containing Mg, Mg contained in the brazing material evaporates, thereby creating voids or pin holes (hereinafter, collectively referred to as these) in the first layer 31. Therefore, there is concern that voids) may occur. FIG. 7 illustrates an enlarged cross-sectional photograph of the bonding layer including voids 33L generated due to evaporation of Mg, etc. In FIG. 7, the presence of a void 33L having an equivalent circle diameter (diameter of a circle with an area equivalent to the cross-sectional area of the void) of 8 μm or more can be confirmed within a field of view of approximately 3500 μm ² . In addition, the equivalent circular diameter of the void 33L in the upper right corner of Fig. 7 is about 9 to 10 μm, the equivalent circular diameter of the void 33L in the upper left corner is 5 μm or more, and the equivalent circular diameter of the void 33L in the upper left corner of Fig. 7 is about 9 to 10 μm. The equivalent circle diameter of the void 33L is about 3 to 4 μm.

The presence of the void 33L having such a large size becomes a factor that reduces the bonding strength between the copper material 10 and the ceramic material 20. Here, in the case of joining the copper material 10 and the ceramic material 20, when a brazing material containing Mg and the above-mentioned active metal element alone and not containing Cu is used, the Mg contained in the brazing material evaporates violently. Therefore, the generation of voids 33L with an equivalent circular diameter exceeding 8 μm in the first layer 31 becomes inevitable, and as a result, the bonding strength between the copper material 10 and the ceramic material 20 is significantly reduced. becomes degraded. Also, in this case, the joining of the copper material 10 and the ceramic material 20 may become impossible.

In response to this problem, in this embodiment, by using a brazing material 50 that not only contains Mg and an active metal element, but also contains Cu in a ratio described later, at the time of bonding, a void 33L of a large size is formed, For example, it was succeeded in sufficiently suppressing the appearance of voids 33L having an equivalent circular diameter of 8 μm or more in the bonding layer 30.

For example, in Fig. 2(a), within a field of view of approximately 10000 ㎛ ² , not a single void 33S with an equivalent circle diameter of 3 ㎛ or more is observed, and furthermore, there is no void 33S with an equivalent circle diameter of 1 to 1 μm. There are only three voids 33S with a size of about 2㎛. For example, in Figure 2(b), within a field of view of approximately 10000 ㎛ ² , the number of voids 33S with a circle-equivalent diameter of about 2.5 ㎛ is only one, and There are only two voids 33S with a diameter of about 1 to 2 μm.

As such, the bonding layer 30 in this embodiment is within an arbitrary field of view of approximately 10000 ㎛ ² when the first layer 31 is observed in a cross section perpendicular to the bonding surfaces 10s and 20s, It has an extremely excellent characteristic in that not a single void 33L with an equivalent circle diameter of 8 μm or more is observed.

In this embodiment, when the first layer 31 is observed in a cross section perpendicular to the joint surfaces 10s and 20s, even if voids 33S are observed, the equivalent circle diameter is less than 8 μm. It is converged and has a size of, for example, less than 5 μm, preferably less than 3 μm.

In addition, in this embodiment, when the first layer 31 is observed in a cross section perpendicular to the bonding surfaces 10s and 20s, a void 33S with a circular equivalent diameter of less than 8 μm, for example, a circular equivalent size, is formed. There may be cases where voids 33S with a diameter of more than 2 μm and less than 8 μm are observed, but the number of voids is 10 or less, preferably 5 or less, within any field of view of approximately 10000 μm ² . , there is very little. In addition, in this embodiment, there may be cases where voids 33S with an equivalent circular diameter of 1 μm or more and 2 μm or less are observed, but the number of voids 33S is 20 within an arbitrary field of view of approximately 10000 μm ² . Hereinafter, it is very small, preferably 10 or less.

(Feature 3)

Among the bonding layers 30, the second layer 32 constituting the interface with the ceramic material 20 contains titanium nitride (TiN), which is a nitride of an active metal element (Ti as an example here), as its main component. When the ceramic material 20 is made of silicon nitride, the second layer 32 may contain a compound represented by the compositional formula Ti ₅ Si ₃ .

Additionally, in this embodiment, the second layer 32 contains nitride crystal X represented by the composition formula MgSiN ₂ . Additionally, as shown in FIG. 3 , the nitride crystals X are localized near the interface with the ceramic material 20 in the second layer 32 .

The thickness of the region where the nitride crystals For example, as shown in FIG. 3, when the thickness Tx of the second layer 32 is about 250 nm, the thickness of the region where the nitride crystals It is about ㎚.

The presence of the nitride crystal

In addition, the second layer 32 in this embodiment does not substantially contain nitride crystal Y represented by the composition formula Mg ₃ N ₂ . Nitride crystal Y cannot be confirmed even if analysis is performed using the TEM-PED method.

(Feature 4)

By having these various features, in this embodiment, it has succeeded in significantly increasing the bonding strength between the copper material 10 and the ceramic material 20.

Specifically, the shear strength of the bonding layer 30 in this embodiment is 10 MPa or more, preferably 50 MPa or more. In addition, the tensile strength of the bonding layer 30 in this embodiment is 17.3 MPa or more, preferably 86.6 MPa or more.

In addition, the shear strength of the bonding layer 30 referred to here refers to the direction parallel to the bonding surfaces 10s and 20s of the copper material 10 and the ceramic material 20, as shown in FIG. 4(a). When stress (shear stress) is applied to the bonding layer 30 so as to cause displacement in opposite directions, the shear per unit area required to fracture (shear failure) the bonding layer 30 It means the magnitude of stress. In addition, the tensile strength of the bonding layer 30 refers to the strength of the copper material 10 and the ceramic material 20 to each other along the direction perpendicular to the bonding surfaces 10s and 20s, as shown in (b) of FIG. 4. When stress (tensile stress) is applied to the bonding layer 30 for separation, it means the magnitude of the tensile stress per unit area required to fracture (peel fracture) the bonding layer 30.

(2) Manufacturing method of copper ceramic bonded body

Next, the manufacturing method of the above-described copper ceramic joined body 100 will be explained using FIGS. 5(a) to 5(c).

First, as shown in FIG. 5(a), the copper material 10 described above and the ceramic material 20 described above are arranged to be laminated with the brazing material 50 interposed therebetween.

As the brazing material 50, as described above, a material containing 65 to 95 at% Cu, 4.5 to 33 at% Mg, and the above-mentioned active metal elements in a total ratio of 0.1 to 7 at% can be used.

Cu contained in the brazing material 50 acts to develop the various characteristics described above in the bonding layer 30 formed when the brazing material 50 reacts with the copper material 10 and the ceramic material 20. In addition, Mg contained in the brazing material 50 affects the wettability of the copper material 10 and the brazing material 50 and the ceramic material 20 and the brazing material 50 when joining the copper material 10 and the ceramic material 20. ) acts to increase the wettability of the product in a well-balanced manner. In addition, the active metal element contained in the brazing material 50 reacts with the ceramic material 20 to form the second layer 32 to increase the bonding strength between the bonding layer 30 and the ceramic material 20. It works.

In addition, when the Mg content contained in the brazing material 50 is less than 4.5 at%, or the total active metal element content is less than 0.1 at%, or the Cu content exceeds 95 at%, the above-mentioned Mg addition The effect due to the addition of the active metal element or the effect due to the addition of the active metal element will not be obtained.

In addition, when the Mg content in the brazing material 50 exceeds 33 at%, the total active metal element content exceeds 7 at%, or the Cu content is less than 65 at%, the effect of adding Cu as described above cannot be obtained. For example, the above-described SA and SB do not satisfy the relational expression SA/(SA+SB)>0.6, and the second layer 32 and the copper material 10 are connected among the first layer 31. It becomes impossible to secure a pass made by the employer (31A). Also, for example, when the first layer 31 is observed in a cross section perpendicular to the joint surfaces 10s and 20s, a void 33L with an equivalent circular diameter of 8 μm or more appears. _Additionally , for example, nitride crystals As a result of these, the shear strength and tensile strength of the bonding layer 30 are greatly reduced, the shear strength becomes less than 10 MPa and the tensile strength becomes less than 17.3 MPa, and further, the copper material 10 and the ceramic material 20 In some cases, the bond actually fails.

From these, the addition amount of Cu, Mg, and active metal elements contained in the brazing material 50 is 65 to 95 at% of Cu, 4.5 to 33 at% of Mg, and 0.1 to 7 at% of the above-mentioned active metal elements in total. It is desirable to set the amount within the range.

In addition, Cu is in at least one form among simple substance (Cu crystal), hydride (CuH), intermetallic compound with Mg (MgCu ₂ ), and intermetallic compound with active metal element (for example, Cu-Ti compound). It can be included as . Mg can be included in at least one form among simple substance (Mg crystal), hydride (MgH ₂ ), intermetallic compound with Cu (MgCu ₂ ), and compound with active metal element (for example, Mg-Ti compound). You can. For example, when Ti is selected, the active metal element can be included in at least any form among simple substance (Ti crystal), hydride (TiH ₂ ), intermetallic compound with Cu, and intermetallic compound with Mg.

The brazing material 50 preferably contains Mg not in the form of Mg alone, but in the form of an intermetallic compound with Cu (MgCu ₂ ). In addition, the brazing material 50 preferably contains Cu in the form of Cu alone and an intermetallic compound with Mg (MgCu ₂ ). When the brazing material 50 has a eutectic composition of Cu-MgCu ₂ , it becomes possible to lower the melting point of the brazing material 50. In addition, this allows the heating temperature at the time of joining to be lowered, and rapid evaporation of Mg can be avoided. As a result, it becomes possible to more reliably express the various characteristics described above in the formed bonding layer 30.

The form of the brazing material 50 may be any of powder form, thin form, or paste form. In the case of powder form, the average particle diameter (D50) of the powder can be, for example, 5 to 50 μm. When it is in the form of a thin film, the average film thickness can be, for example, 5 to 200 μm. In the case of a paste-like form, alcohols such as terpineol and butanediol and toluene are used as the main solvent, polyvinyl alcohol, ethyl cellulose, polymethacrylic acid, polyacrylic, etc. are used as a binder, and cations are used as a surfactant. Systemic, anionic, and nonionic activators can be used. It may further contain a plasticizer or dispersant.

Methods for arranging the brazing material 50 on the planned joining surfaces 10s' and 20s' of the copper material 10 and the ceramic material 20 include screen printing, transfer, dispensing, inkjet, spray coating, sputtering, and vapor deposition. Known methods can be used.

Subsequently, as shown in (b) of FIG. 5, the laminate 100' of the copper material 10 and the ceramic material 20 disposed with the brazing material 50 interposed is pressed in the stacking direction, It is heated and maintained under a predetermined atmosphere.

The conditions are exemplified below.

Atmosphere: Any of reduced pressure atmosphere, inert gas atmosphere, reducing atmosphere

Oxygen concentration: 1000 ppm or less, preferably 300 ppm or less, more preferably 30 ppm or less.

Pressurized: above 0.5kPa

Heating temperature: 735℃ or higher and 900℃ or lower

Holding time: There is no particular limitation, for example, 3 minutes or more and 120 minutes or less.

At the time of heating, it is necessary that a liquid phase is formed in a part of the brazing material 50, and in addition, the active metal element must be melted in the liquid phase. This state can be created by setting the heating temperature to 735°C or higher. However, if the heating temperature is too high, evaporation of Mg may become severe, making liquid phase formation difficult, or voids 33L may be generated in the formed bonding layer 30. By setting the heating temperature to 900°C or lower, it becomes possible to avoid such problems. By setting the pressurization to 0.5 kPa or more, it is possible to maintain close contact between the copper material 10 and the ceramic material 20 via the brazing material 50, thereby increasing the bonding strength between the copper material 10 and the ceramic material 20. It becomes possible. There is no particular limitation on the upper limit of pressurization, but for example, it can be about 2.0 kPa. Since the oxygen component contained in the atmosphere is a factor that oxidizes the active metal elements and Mg, it is preferable that it is lower. By setting the concentration within the above-mentioned range, it becomes possible to solve this problem.

Thereafter, the heated laminate 100' is cooled. As a result, as shown in Figure 5(c), a copper ceramic bonded body 100 having the various characteristics described above is manufactured.

(3) Effect

According to this aspect, one or more of the effects shown below are obtained.

(a) The first first It becomes possible to avoid local generation of the compound phase 31B in the layer 31 (for example, local generation in the region D near the interface described above). As a result, when the first layer 31 is observed in a cross section perpendicular to the joint surfaces 10s and 20s, the total cross-sectional area of the solid solution phase 31A in the area D near the interface adjacent to the second layer 32 is SA and the total cross-sectional area SB of the compound phase (31B) satisfy the relational expression SA/(SA+SB)>0.6. In addition, in the first layer 31, a path made of the solid solution phase 31A connecting the second layer 32 and the copper material 10 is secured.

(b) By joining the copper material 10 and the ceramic material 20 using the brazing material 50 described above, it becomes possible to suppress the generation of voids 33L in the first layer 31. As a result, when the first layer 31 was observed in a cross section perpendicular to the joint surfaces 10s and 20s, voids 33L with an equivalent circular diameter of 8 μm or more were not observed within a field of view of 10000 μm ² . It won't happen.

(c) By bonding the copper material 10 and the ceramic material 20 using the above-described brazing material 50, it is possible to include nitride _crystals It becomes. In addition, it is also possible to localize this nitride crystal X near the interface with the ceramic material 20 in the second layer 32.

(d) At least one of these various features makes it possible to dramatically increase the bonding strength between the copper material 10 and the ceramic material 20. For example, it becomes possible to set the shear strength of the bonding layer 30 to 10 MPa or more, preferably 50 MPa or more. Additionally, it becomes possible to set the tensile strength of the bonding layer 30 to 17.3 MPa or more, preferably 86.6 MPa or more.

<Other aspects of the present disclosure>

Above, aspects of the present disclosure have been described in detail. However, the present disclosure is not limited to the above-described aspects, and various changes can be made without departing from the gist.

As a material for the ceramic material 20, an example of using silicon nitride or aluminum nitride has been described, but it is not limited to these, and may include alumina (Al ₂ O ₃ ), silicon carbide (SiC), and boron carbide (B ₄ C). , ZTA (zirconia reinforced alumina), diamond, etc. may be used. Even in these cases, the technology of the present disclosure can be applied, and the same effect as the above-described aspect is obtained.

As a metal material to be joined to the ceramic material 20, an example of using the copper material 10 made of Cu or a Cu alloy has been described, but it is not limited to these, and a nickel material made of Ni or a Ni alloy may be used. . Even in this case, the technology of the present disclosure can be applied, and the same effect as the above-described aspect is obtained.

The copper ceramic bonded body in this embodiment is not limited to the use of an insulating circuit board, but can be widely applied to a variety of applications, such as heat sinks and component parts of internal combustion engines and power generation machines. In this way, the same effect as the above-described embodiment is obtained.

[Example]

(Samples 1 to 20)

As a ceramic material, a plate made of silicon nitride with a thickness of 0.3 mm was used, and as a copper material, a plate made of oxygen-free copper with a thickness of 2.0 mm was used. As the brazing material, a paste obtained by mixing Cu-Mg alloy powder, Cu powder, and TiH ₂ powder in a predetermined ratio was used. When forming a paste, polyethylene glycol and diethylene glycol monobutyl ether with a molecular weight of 400 or less were used as solvents, and the ratio of the solvent in the paste was 9 mass%. The element mixing ratio of Cu:Mg:Ti in the paste was as shown in Table 1. This paste is applied using screen printing on the planned joining surface of the ceramic material, a copper material is placed directly on top of the applied paste film, and is pressed with a force of 8 kPa along the stacking direction, and a pressure of 1.0×10 ^-2 Pa or less is applied. Samples 1 to 20 were produced by heat treatment in a vacuum atmosphere under the conditions shown in Table 1.

Then, for samples 1 to 20, the first layer was observed in a cross section perpendicular to the bonding surfaces 10s and 20s, and in the area near the interface toward the copper material side from the interface with the second layer, the above-described SA/( The cross-sectional area ratio expressed as SA+SB) was measured. This observation was made using FE-SEM and EDX. The phase in which the main phase was Cu was confirmed from EDX, and this was designated as the solid solution phase, and the phase in which the contrast of the reflected electron image was different from that of the solid solution phase was designated as the compound phase. These total cross-sectional areas and their ratios were calculated using image analysis software “Image J (registered trademark).” The analysis range was 10 μm from the interface with the second layer, and the width was 90 μm.

Subsequently, a shear strength test of the bonding layer was performed. In this test, first, for the obtained samples 1 to 20 (copper-ceramic bonded body), the copper material was processed into a cylindrical shape with a diameter of 3 mm and a height of 2 mm, and the bonding surface of the surrounding ceramic material was exposed. A test piece was produced. Then, as shown in FIG. 6, in a state in which the ceramic material of the test piece is fixed, the cylindrical copper material is pressed using a displacement jig along a direction parallel to the joint surface, and the joint layer is fractured (shear fracture). The magnitude of the stress when reaching was measured, and based on the value, the shear strength of the bonding layer was calculated. In addition, the shear test position (contact height H of the displacement jig) was set at a height of 200 μm from the exposed surface of the ceramic material, and the moving speed of the displacement axis was set at 100 μm/s.

Additionally, based on the results of the shear strength test, the tensile strength of the bonding layer was calculated. The tensile strength of the bonding layer can be converted from the shear strength using the von Mises equation, and its magnitude is approximately 1.73 times the shear strength.

Table 1 shows these results.

As shown in Table 1, it was confirmed that in all of Samples 1 to 20, the cross-sectional area ratio expressed as SA/(SA+SB) exceeded 0.6. In addition, it was confirmed that the shear strength of all samples was 10 MPa or more (50 MPa or more in these samples), and the tensile strength converted based on this was 17.3 MPa or more (86.6 MPa or more in these samples).

In addition, as a result of cross-sectional observation, in Samples 1 to 20, all were as follows: (1) in the first layer, a path consisting of a solid solution connecting the second layer and the copper material was secured, and (2) approximately 10000 μm. ^2. Within the field of view, not a single void with an equivalent circle diameter of 8 μm or more is observed in the first layer; (3) within the field of view, no voids with an equivalent circle diameter of more than 2 μm are observed in the first layer; 8 Even if voids with a size of less than ㎛ are observed, the number is 10 or less, preferably 5 or less, (4) Within the field of view, in the first layer, the equivalent circle diameter is 1 ㎛ or more and 2 ㎛ or less. Even if phosphorus voids are observed, the number is 20 or less, preferably 10 or less, (5) the second layer contains _nitride crystals It was also confirmed that

(Samples 21 and 22)

Similarly to Samples 1 to 20, a plate made of silicon nitride with a thickness of 0.32 mm was used as a ceramic material, and a plate made of oxygen-free copper with a thickness of 2 mm was used as a copper material. As a brazing material, a paste was used that did not contain Cu powder but mixed Mg powder and TiH ₂ powder in a predetermined ratio to form a paste. When forming a paste, as in Samples 1 to 20, polyethylene glycol and diethylene glycol monobutyl ether with a molecular weight of 400 or less were used as solvents, and the ratio of the solvent in the paste was 9 mass%. The element mixing ratio of Cu:Mg:Ti in the paste was as shown in Table 1. This paste is applied to the planned joint surface of the ceramic material using screen printing, a copper material is placed directly on top of the applied paste film, and pressurized with a force of 8 kPa along the stacking direction, and vacuumed at 1.0 × 10 ^-2 Pa or less. Heat treatment was performed under the conditions in Table 1 in an atmosphere to produce samples 21 and 22.

Then, a shear strength test was performed on samples 21 and 22 by the method described above. As the results are shown in Table 1, the shear strength was 0.5 MPa or less and the tensile strength was 0.9 MPa or less, and it was confirmed that practical bond strength was not obtained in these samples (substantially non-bonded). Additionally, since these samples did not have a bonding strength that could withstand processing for cross-sectional structure observation, the bonding layer could not be observed in a cross section perpendicular to the bonding surface.

<Preferred embodiments of the present disclosure>

Hereinafter, preferred embodiments of the present disclosure will be described.

According to one aspect of the present disclosure,

A copper material made of Cu or Cu alloy,

A ceramic material bonded to the copper material and made of Si or Al nitride,

It is formed on the joint surface of the copper material and the ceramic material, and includes Cu and Mg, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ca, Y, Ce, La, Sm, Yb, It has a bonding layer further containing at least one active metal element selected from the group consisting of Nd, Gd, and Er,

The shear strength of the bonding layer is 10 MPa or more (preferably 50 MPa or more).

A copper ceramic joint is provided.

Preferably,

The tensile strength of the bonding layer is 17.3 MPa or more (preferably 86.6 MPa or more).

Also preferably,

The bonding layer is

A first layer that constitutes an interface with the copper material and includes a solid solution phase formed by Mg being dissolved in Cu;

It has a second layer that constitutes an interface with the ceramic material and contains a nitride of the active metal element,

The first layer further includes a compound phase containing an intermetallic compound of Cu and Mg,

When the first layer is observed in a cross section perpendicular to the joint surface, in the area near the interface adjacent to the interface with the second layer, the total cross-sectional area SA of the solid solution phase and the total cross-sectional area SB of the compound phase are,

SA/(SA+SB)>0.6, preferably >0.7, and more preferably >0.8 are satisfied.

Preferably,

The first layer has a path consisting of the solid solution phase connecting the second layer and the copper material.

Preferably,

When the first layer is observed in a cross section perpendicular to the bonding surface, no voids having an equivalent circle diameter of 8 μm or more are observed within any field of view of 10000 μm ² .

Preferably,

When the first layer is observed in a cross section perpendicular to the joint surface, the number of voids with an equivalent circle diameter of more than 2 μm and less than 8 μm in an arbitrary field of view of 10000 μm ² is 10 or less, preferably 10 or less. is 5 or less, and the number of voids with an equivalent circle diameter of 1 μm to 2 μm is 20 or less, preferably 10 or less.

Preferably,

The second layer contains nitride crystal X represented by the composition formula MgSiN ₂ .

Preferably,

The nitride crystal X is localized in the second layer near the interface with the ceramic material.

Preferably,

The second layer does not substantially contain nitride crystal Y represented by the composition formula Mg ₃ N ₂ .

According to another aspect of the present disclosure,

It is used for joining a copper material made of Cu or Cu alloy and a ceramic material made of nitride of Si or Al,

Cu at 65 to 95 at%, Mg at 4.5 to 33 at%, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ca, Y, Ce, La, Sm, Yb, Nd, Gd, Er. Containing at least one active metal element selected from the group consisting of a total ratio of 0.1 to 7 at%

Lead material is provided.

Preferably,

Mg is included (not in the form of Mg alone) in the form of an intermetallic compound with Cu (MgCu ₂ crystal).

Preferably,

Cu is included in the form of Cu alone and an intermetallic compound with Mg.

According to another aspect of the present disclosure,

It is a copper material bonded to a ceramic material made of Si or Al nitride,

Made of Cu or Cu alloy,

On the surface to be joined to the ceramic material, 65 to 95 at% of Cu, 4.5 to 33 at% of Mg, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ca, Y, Ce, La, A layer formed of a brazing material containing at least one active metal element selected from the group consisting of Sm, Yb, Nd, Gd, and Er in a total ratio of 0.1 to 7 at%.

Copper material with brazing material is provided.

According to another aspect of the present disclosure,

It is a ceramic material bonded to a copper material made of Cu or Cu alloy,

It is made of nitride of Si or Al,

On the surface to be joined to the copper material, 65 to 95 at% of Cu, 4.5 to 33 at% of Mg, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ca, Y, Ce, La, A layer formed of a brazing material containing at least one active metal element selected from the group consisting of Sm, Yb, Nd, Gd, and Er in a total ratio of 0.1 to 7 at%.

A ceramic material with brazing material is provided.

According to another aspect of the present disclosure,

A process of arranging a copper material made of Cu or a Cu alloy and a ceramic material made of a nitride of Si or Al to be laminated with a brazing material interposed therebetween;

A step of heating and holding the laminate of the copper material and the ceramic material while pressing in the stacking direction,

As the brazing material, 65 to 95 at% Cu, 4.5 to 33 at% Mg, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ca, Y, Ce, La, Sm, Yb, Nd, Using a material containing at least one active metal element selected from the group consisting of Gd and Er in a total ratio of 0.1 to 7 at%

A method for manufacturing a copper ceramic joint is provided.

100: Copper ceramic joint
100': Laminate
10: Copper material
10s: joint surface
20: Ceramic material
20s: joint surface
30: bonding layer
31: first layer
31A: Employment awards
31B: Compound phase
32: second layer
33L: Void (equivalent circle diameter 8㎛ or more)
33S: Void (equivalent circle diameter less than 8㎛)
50: brazing material
D: Area near the interface
X: Nitride crystal

Claims (13)

A copper material made of Cu or Cu alloy,
A ceramic material bonded to the copper material and made of Si or Al nitride,
It is formed on the joint surface of the copper material and the ceramic material, and includes Cu and Mg, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ca, Y, Ce, La, Sm, Yb, It has a bonding layer further containing at least one active metal element selected from the group consisting of Nd, Gd, and Er,
A copper ceramic bonded body wherein the bonding layer has a shear strength of 10 MPa or more. According to paragraph 1,
A copper ceramic bonded body wherein the tensile strength of the bonding layer is 17.3 MPa or more. According to claim 1 or 2,
The bonding layer is
A first layer that constitutes an interface with the copper material and includes a solid solution phase formed by Mg being dissolved in Cu;
It has a second layer that constitutes an interface with the ceramic material and contains a nitride of the active metal element,
The first layer further includes a compound phase containing an intermetallic compound of Cu and Mg,
When the first layer is observed in a cross section perpendicular to the joint surface, in the area near the interface adjacent to the interface with the second layer, the total cross-sectional area SA of the solid solution phase and the total cross-sectional area SB of the compound phase are,
A copper ceramic joint that satisfies the relationship SA/(SA+SB)>0.6. According to paragraph 3,
A copper ceramic joined body in which the first layer has a path made of the solid solution phase connecting the second layer and the copper material. According to paragraph 3,
A copper ceramic bonded body in which, when the first layer is observed in a cross section perpendicular to the bonding surface, no voids having an equivalent circle diameter of 8 μm or more are observed within an arbitrary field of view of 10000 μm ² . According to clause 5,
When the first layer is observed in a cross section perpendicular to the bonding surface, the number of voids with an equivalent circle diameter of more than 2 μm and less than 8 μm in an arbitrary field of view of 10000 μm ² is 10 or less. . According to paragraph 3,
A copper ceramic bonded body in which the second layer contains nitride crystals X represented by the composition formula MgSiN ₂ . In clause 7,
A copper-ceramic bonded body in which the nitride crystal X is localized in the second layer near an interface with the ceramic material. According to paragraph 3,
A copper ceramic bonded body wherein the second layer does not substantially contain nitride crystal Y represented by the composition formula Mg ₃ N ₂ . It is used for joining a copper material made of Cu or Cu alloy and a ceramic material made of nitride of Si or Al,
Cu at 65 to 95 at%, Mg at 4.5 to 33 at%, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ca, Y, Ce, La, Sm, Yb, Nd, Gd, Er. A brazing material containing at least one active metal element selected from the group consisting of a total of 0.1 to 7 at%. According to clause 10,
A brazing material containing Mg in the form of an intermetallic compound with Cu. According to claim 10 or 11,
A brazing material containing Cu in the form of Cu alone and an intermetallic compound with Mg. A process of arranging a copper material made of Cu or a Cu alloy and a ceramic material made of a nitride of Si or Al to be laminated with a brazing material interposed therebetween;
A step of heating and holding the laminate of the copper material and the ceramic material while pressing in the stacking direction,
As the brazing material, 65 to 95 at% Cu, 4.5 to 33 at% Mg, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ca, Y, Ce, La, Sm, Yb, Nd, A method of producing a copper ceramic bonded body using a material containing at least one active metal element selected from the group consisting of Gd and Er in a total ratio of 0.1 to 7 at%.